Revert "Bug 1980240 - Refactor tabs drag and drop code into its own module r=tabbrowser-reviewers,sthompson" for causing bc failures @ browser_tabdetach.js

This reverts commit 6eba594.

Author: Sandor Molnar

browser/base/content/browser-main.js

@@ -21,7 +21,6 @@
   Services.scriptloader.loadSubScript("chrome://browser/content/sidebar/browser-sidebar.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/browser-customtitlebar.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/browser-unified-extensions.js", this);
-  Services.scriptloader.loadSubScript("chrome://browser/content/tabbrowser/drag-and-drop.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/tabbrowser/tab.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/tabbrowser/tabbrowser.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/tabbrowser/tabgroup.js", this);

browser/components/tabbrowser/TabsList.sys.mjs

@@ -706,13 +706,9 @@ export class TabsPanel extends TabsListBase {
         ? getTabGroupFromRow(row).labelElement
         : getTabFromRow(row);
 
-    this.gBrowser.tabContainer.tabDragAndDrop.startTabDrag(
-      event,
-      elementToDrag,
-      {
-        fromTabList: true,
-      }
-    );
+    this.gBrowser.tabContainer.startTabDrag(event, elementToDrag, {
+      fromTabList: true,
+    });
   }
 
   /**
@@ -728,8 +724,7 @@ export class TabsPanel extends TabsListBase {
    * @returns {boolean}
    */
   _isMovingTabs(event) {
-    var effects =
-      this.gBrowser.tabContainer.tabDragAndDrop.getDropEffectForTabDrag(event);
+    var effects = this.gBrowser.tabContainer.getDropEffectForTabDrag(event);
     return effects == "move";
   }